This is a common problem. See this thread. In short, even if you have DirectX 10, that doesn't mean you have all of DirectX 9, because of "optional" updates to DirectX 9 (which really are required by Construct, I wish Microsoft wouldn't call them optional!)

You really should just install the version of directX that comes with Construct. Having just those dll's may allow the program to start, but you may encounter problems down the road. Installing the DirectX 9 package won't overwrite DirectX10.